I guess the thing I wonder hearing this is what is the consequence of being dropped. That is, I could see an office deciding that someone who hasn't been there for 6 years isn't a patient any more. However, let's say that person calls the next week and wants to make an appointment. Why wouldn't they just take you at that point? That is, take you as a "new" patient. Or, is it that the doctor isn't taking any new patients?
I did several years ago call a doctor that I hadn't seen in a few years and they had put my records into off site storage so from their standpoint I would guess they didn't consider me an active patient. But, they easily took me back and got my records back so it was no big deal.